DE102012220289A1 - Fuel tank ventilation system for car, has navigation system recognizing travel path lying ahead of car, where purging of intermediate storage is carried out by taking type of travel path lying ahead of car into account - Google Patents

Abstract

The system has an intermediate storage for volatile fuel components purged by fresh air supplied by a latch through a consumer depending on boundary conditions. A navigation system equipped in a car recognizes a travel path lying ahead of the car, where the purging of the intermediate storage is carried out by taking the type of travel path lying ahead of the car into account. The type of travel path lying ahead of the car is set in comparison with the type of the current travel path of the car.

Description

The invention relates to a tank ventilation system of a motor vehicle with a buffer for volatile fuel components, which is purged depending on boundary conditions by fresh air through the buffer is supplied to a consumer of (located in the tank of the motor vehicle) fuel, and wherein the motor vehicle further with a navigation system or The like is equipped, which knows a route ahead of the vehicle. The state of the art is in addition to the DE 101 31 798 A1 on the DE 10 2007 030 523 A1 directed.

The technology of temporary storage of volatile fuel constituents in motor vehicles, usually in so-called activated carbon filters, is well known to the person skilled in the art. As is known, such charcoal filters or intermediate storage must be repeatedly flushed in order to achieve a so-called "breakthrough" with which the volatile fuel constituents evaporating in the fuel tank (in short: "tank") of the motor vehicle and stored in the activated carbon filter would escape unburned into the environment avoid. Since flushing of the buffer for the operation, in particular of an internal combustion engine and generally a consumer, which or which is supplied from the tank with fuel, may be unfavorable under certain conditions, for the initiation or implementation of such a flushing process, with which the internal combustion engine or the consumer, the cached volatile fuel components are supplied together with fresh air for combustion, various boundary conditions are taken into account. For this purpose, for example, the above-mentioned first DE 101 31 798 A1 directed.

In the above mentioned further DE 10 2007 030 523 A1 a method for venting or venting a fuel tank of a motor vehicle in connection with a planned filling of the fuel tank is described at a gas station, which may be in the tank overpressure or negative pressure and is determined by means of a positioning system, whether the motor vehicle near or at a gas station located. If so, bleeding or venting is permitted or carried out, with a temporary storage (charcoal filter) being exposed to volatile fuel components. For this purpose, the motor vehicle according to the DE 10 2007 030 523 A1 a navigation system or another, in particular satellite-supported position determining device, wherein an electronic control unit to access information about the geographical positions of gas stations and can compare the current position of the motor vehicle with these.

The present invention also relates to a tank ventilation system of a motor vehicle, which is equipped with a navigation system or the like, but it does not have to be a satellite-supported position determination system, but to a suitable system or an electronic control unit, which or which a preceding route of the Vehicle knows. For example, a route ahead may also be derived from repetitive "behavioral patterns", for example, if the vehicle is moved by the driver every working day early in the morning and at the end of the workday on a substantially identical route. Conventional navigation systems in which the road network is stored and in which the driver can directly or indirectly enter a destination, which he would like to reach or start from his current position, whereupon the navigation system proposes a suitable route, are of course the term "navigation system or the like ".

For a vehicle with a navigation system (in the broadest sense, ie or the like) hereby a further improvement for a tank ventilation system according to the preamble of claim 1 is shown, with which the probability of unwanted breakage of the buffer can be further reduced and at the same time the consumer of the Fuel as far as possible in operating conditions favorable for its operation is subjected to a flushing process or rinsing is carried out in for a flushing generally favorable operating conditions of the consumer (= object of the present invention). In other words, it should be shown how a buffer can be flushed so that the cached fuel components do not get into the environment and essentially only the consumer, which is usually an internal combustion engine acting as a vehicle drive unit, be fed when the flushing process can be carried out in a favorable manner, especially if this flushing of the buffer does not or not significantly affect the operation of the consumer or the internal combustion engine.

The solution to this problem is characterized in that the type of the preceding route is taken into account for flushing the buffer. Advantageous embodiments and further developments are content of the dependent claims.

According to the invention is taken into account for determining a favorable or optimized rinsing strategy for the cache of or in an electronic control unit, which type is the preceding, ie soon to be traveled route of the motor vehicle, preferably taking into account or compared to the current type of driving plug. This electronic control unit thereupon controls a suitable flushing valve or the like suitably, which flushing valve (or the like.) Prevents a connection from the buffer to the internal combustion engine of the motor vehicle (in general: to a consumer) or otherwise rinsing the otherwise locked for a flushing buffer allows. The favorable or optimized rinsing strategy is designed so that on the one hand breakage of the buffer is prevented as much as possible and on the other hand, the operation of the consumer is affected by the rinsing process as little as possible and / or a rinsing process can be carried out in a favorable manner can.

For example, when driving on a highway, when the operating as a drive unit of the motor vehicle internal combustion engine (as a consumer) is charged higher, a buffer, in particular an activated carbon filter, be optimally rinsed. The same applies (in a somewhat weakened form) in general for cross-country journeys, d. H. when the motor vehicle is moved outside closed villages. In city traffic, however, due to the there taking place many load changes of the internal combustion engine, a flushing of the buffer lead to impairments of a quiet and smooth running of an internal combustion engine, or it is idle operation of an internal combustion engine no meaningful flushing of the buffer possible. Accordingly, it can be provided that with respect to the nature of the route ahead, a distinction is made between trips outside and within closed towns, and that when driving outside a village (as "current route") shortly before a foreseeable entrance to a village (as Fahrtstrecke ") the buffer is completely rinsed. The fact that an entry into a village is imminent can easily be ascertained with an electronic navigation system which knows the current position of the vehicle and the upcoming route, for example by means of a destination input previously entered by the driver of the motor vehicle.

Practically the same as for journeys outside or within localities applies, if a distinction is made with regard to the constant-running part of journeys. Constant driving is a driving state in which no significant load changes of the internal combustion engine (as a consumer) and in particular no significant load reduction takes place or takes place, ie. H. when the vehicle is driven by the internal combustion engine at a substantially constant speed. A low cruise component is thus characterized by greatly varying speeds and is much less suitable for flushing the buffer (and therefore to avoid as much as possible) as a route with a high cruise component, on which preferably a rinsing process is performed. In particular, a distinction between free travel and stop-and-go traffic can be distinguished in this sense, with purging being avoided as long as possible in the stop-and-go traffic and preferably always carried out when evaluated by evaluating the appropriate data of a navigation system or Like. By an electronic control unit, a high probability of a free ride is detected. Whether a free ride or "stop-and-go traffic" (ie traffic in traffic jams) is to be expected, can be easily determined with modern navigation systems, which continue to receive information about impending traffic congestion or traffic density.

Furthermore, it can be provided in a tank ventilation system according to the invention that before a predictable uphill rinsing of the buffer is performed, since in an uphill due to the decreasing ambient air pressure, an increased fuel output is expected in the fuel tank. Consequently, it is desirable to empty the cache as far as possible before the start of the uphill, so that it can accommodate a large amount of volatile fuel components.

Generalizing the concrete case of a mountain trip, a tank ventilation system according to the invention can take into account the altitude above sea level and / or the ambient temperature as another boundary condition, since both variables influence the outgassing tendency of the fuel in the tank. At lower outgassing tendency of the cache or the activated carbon filter must of course be flushed less often than at higher output slope. As a further boundary condition, furthermore, the loading state of the buffer can be taken into account if this is determined in a suitable manner. For example, various methods for measuring the loading state of an activated carbon filter are known to those skilled in the art; Alternatively, its load condition can also be estimated.

In terms of an advantageous development of a tank ventilation system according to the invention, the consumer can be operated during flushing of the buffer in this appropriate manner, the term of the operation of the Consumer is very general. For example, a connection of an auxiliary engine driven directly or indirectly by an internal combustion engine (as a consumer) should fall under this term. The internal combustion engine can thus be operated in a particularly suitable for rinsing the activated carbon filter mode, as soon as the need for a rinsing process has been found according to the invention. In this case, in an electronic control of the internal combustion engine from a consumption-optimized control map to a rinsing air optimized control map, eg. With a gear position for higher speeds, be switched and it can be introduced further measures that required for flushing vacuum in the tank ventilation system is increased. Preferably, other diagnostic functions, in the implementation of which rinsing of the buffer is prevented, suppressed in such a special this mode. Such other diagnostic functions may be, for example, a lambda probe diagnosis or a diagnostic function with respect to an exhaust gas catalyst in addition to a tank ventilation diagnosis.

For example, a part of the route ahead is an uphill trip with subsequent city driving, which was recognized by an electronic control unit via a navigation system (in the broadest sense) as the actual route with active route guidance or as the most likely route due to the (repetitive) typical behavior of the driver. According to the invention, the most favorable operating points for a purging operation are then determined along the route ahead or route for purging of the intermediate store and for the internal combustion engine provided in the respective vehicle type. In these operating points, a flushing process is prioritized, for example by suppression of on-board diagnostics, adaptation of control maps and opening behavior of a tank vent valve or by applying additional loads to the engine and thereby increasing the flushing throughput for activated carbon filter regeneration. This can be counteracted an expected higher fuel outgassing, which must be cached in the activated carbon filter. By parallel detection of the loading of the activated carbon filter (for example, in the steps empty, half full or full), which is performed, for example, via measured values of the lambda probe in the exhaust system of the internal combustion engine, the regeneration of the activated carbon filter can be additionally prioritized by purging. Hereby, a breakthrough of the activated carbon filter or intermediate storage can be safely avoided. Conversely, if there is no increased need for regeneration of the activated carbon filter, the internal combustion engine is preferably operated with a consumption-optimized operating strategy.

In other words, in the present invention, it is a matter of recognizing situations that require increased activated carbon filter regeneration via a navigation system in the broadest sense, using a detected route or typical behavior patterns indicative of a probable route , These situations are referred to as "critical situations" and, as stated above, may be hill climbing or city driving. For the latter, the estimated duration can be determined and the estimated average speed of the vehicle taken into account, whereby traffic jams on the planned route can be considered. Furthermore, in principle, situations can be detected that require increased activated carbon filter regeneration, specifically via the respective operating state of the vehicle or its consumer of the fuel. Thus, longer idle periods of the internal combustion engine can be recognized and taken into account appropriately. Finally, there is a quasi-predictive flushing of the activated carbon filter or temporary storage as soon as a potential risk of breakthrough has been recognized. In particular, the buffer is largely flushed before a critical situation, which could lead to a breakthrough (and thus to fuel odor), to have the full storage capacity of the cache at the beginning of the "critical situation" available.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10131798 A1 [0001, 0002]
• DE 102007030523 A1 [0001, 0003, 0003]

Claims (8)

Tank ventilation system of a motor vehicle with a volatile fuel component buffer, which is purged depending on boundary conditions by fresh air is supplied through the buffer to a consumer, and wherein the motor vehicle is further equipped with a navigation system or the like, which knows a route ahead of the vehicle, characterized characterized in that the type of the preceding route is taken into account for flushing the buffer. Tank ventilation system according to claim 1, characterized in that the type of the preceding route is set in comparison with the type of the current route. Tank ventilation system according to claim 1 or 2, characterized in that it is distinguished with respect to the nature of the route ahead between journeys outside and within closed villages, and that when driving outside a locality shortly before entering a locality of the cache is completely flushed. Tank ventilation system according to one of the preceding claims, characterized in that it is distinguished with respect to the nature of the route ahead with respect to the constant-speed share and carried out at high constant-speed portion of a flushing of the buffer and is avoided as far as possible at low cruise component. Tank ventilation system according to one of the preceding claims, characterized in that prior to a foreseeable uphill rinsing of the buffer is previously performed. Tank ventilation system according to one of the preceding claims, characterized in that the ambient temperature and / or the altitude above sea level is considered as a further boundary condition. Tank ventilation system according to one of the preceding claims, characterized in that as a further boundary condition of the loading state of the buffer is taken into account. Tank ventilation system according to one of the preceding claims, characterized in that the consumer is operated during flushing of the buffer in a suitable manner for this purpose.